Jae Min Chung

Bio: Jae Min Chung is an academic researcher from Korea Forest Service. The author has contributed to research in topics: Genetic diversity & Population. The author has an hindex of 9, co-authored 18 publications receiving 227 citations.

Genetic Diversity in the Common Terrestrial Orchid Oreorchis patens and Its Rare Congener Oreorchis coreana: Inference of Species Evolutionary History and Implications for Conservation

Abstract: We hypothesized that the main Korean mountain ranges provided many refugia for boreal plant species, where they likely found relatively stable habitats and maintained large population sizes. Under this scenario, high levels of genetic variation and low degree of differentiation among populations within these species were anticipated. To test this hypothesis, we examined levels of allozyme diversity (17 loci) in 12 populations of the common terrestrial montane orchid Oreorchis patens from the main ranges in Korea and 4 populations of its rare congener O. coreana, which is restricted to the Korean island of Jeju. As expected, O. patens harbored high levels of genetic variation within populations (%P = 62.8, A = 1.96, H (o) = 0.211, and H (e) = 0.237). Allele frequency differences among populations were low (F (ST) = 0.075), and the species also displayed a significant correlation between pairwise genetic differentiation and geographical distance. All these results suggest that extant populations were founded by multiple genetically diverse individuals and that most of this initial diversity would have been maintained in the stable mountainous conditions during Quaternary climatic oscillations. In contrast, we were unable to detect any genetic diversity in O. coreana, suggesting that contemporary populations likely originated from a single ancestral source population that had lost all genetic variability. From a long-term conservation genetics perspective, extreme rarity and small population sizes, coupled with its apparent genetic uniformity, place O. coreana at a high risk of extinction. Thus, both in situ and ex situ conservation efforts should be of particular importance for this species.

Allozyme variation in Korean populations of Taxus cuspidata (Taxaceae).

Abstract: The genetic diversity and structure of six Korean populations of Taxus cuspidata Sieb. et Zucc., a widespread and dioecious tree native to east Asia, was examined. Although Korean populations are isolated and located over 1000 m a.s.l., they maintain moderate levels of allozyme variation (average percent of loci polymorphic=45%, mean number of alleles per locus=1.78, mean expected heterozygosity=0.192) compared to species with similar life history and ecological traits. In addition, Korean populations harbour slightly higher levels of genetic diversity than populations of T. breuifolia Nutt. in the western United States and Canada. A considerable, high level of heterozygote deficiency was observed in Korean populations of T. cuspidata (mean F IS=0.299). Although significant heterogeneity in allele frequency were detected between populations at all 12 polymorphic loci (p<0.01 at Per-2 and p<0.001 at others), among-population genetic differentiation accounted for 5.6% of the total variation. Indirect estima...

Small-scale spatial genetic structure in the Central African rainforest tree species Aucoumea klaineana: a stepwise approach to infer the impact of limited gene dispersal, population history and habitat fragmentation.

Abstract: Under the isolation-by-distance model, the strength of spatial genetic structure (SGS) depends on seed and pollen dispersal and genetic drift, which in turn depends on local demographic structure. SGS can also be influenced by historical events such as admixture of differentiated gene pools. We analysed the fine-scale SGS in six populations of a pioneer tree species endemic to Central Africa, Aucoumea klaineana. To infer the impacts of limited gene dispersal, population history and habitat fragmentation on isolation by distance, we followed a stepwise approach consisting of a Bayesian clustering method to detect differentiated gene pools followed by the analysis of kinship-distance curves. Interestingly, despite considerable variation in density, the five populations situated under continuous forest cover displayed very similar extent of SGS. This is likely due to an increase in dispersal distance with decreased tree density. Admixture between two gene pools was detected in one of these five populations creating a distinctive pattern of SGS. In the last population sampled in open habitat, the genetic diversity was in the same range as in the other populations despite a recent habitat fragmentation. This result may due to the increase of gene dispersal compensating the effect of the disturbance as suggested by the reduced extent of SGS estimated in this population. Thus, in A. klaineana, the balance between drift and dispersal may facilitate the maintenance of genetic diversity. Finally, from the strength of the SGS and population density, an indirect estimate of gene dispersal distances was obtained for one site: the quadratic mean parent-offspring distance, sigma(g), ranged between 210 m and 570 m.

Low population genetic differentiation in the Orchidaceae: Implications for the diversification of the family

Abstract: A leading hypothesis for the immense diversity of the Orchidaceae is that skewed mating success and small, disjunct populations lead to strong genetic drift and switches between adaptive peaks. This mechanism is only possible under conditions of low gene flow that lead to high genetic differentiation among populations. We tested whether orchids typically exhibit high levels of population genetic differentiation by conducting a meta-analysis to compare mean levels of population genetic differentiation (F(ST)) between orchids and other diverse families and between rare and common orchids. Compared with other families, the Orchidaceae is typically characterized by relatively low genetic differentiation among populations (mean F(ST) = 0.146) at allozyme loci. Rare terrestrial orchids showed higher population genetic differentiation than common orchids, although this value was still lower than the mean for most plant families. All lines of evidence suggest that orchids are typically characterized by low levels of population genetic differentiation, even in species with naturally disjunct populations. As such, we found no strong evidence that genetic drift in isolated populations has played a major role in the diversification of the Orchidaceae. Further research into the diversification of the family needs to unravel the relative roles of biotic and environmental selective pressures in the speciation of orchids.

Increased inbreeding and strong kinship structure in Taxus baccata estimated from both AFLP and SSR data

Abstract: Habitat fragmentation can have severe genetic consequences for trees, such as increased inbreeding and decreased effective population size. In effect, local populations suffer from reduction of genetic variation, and thus loss of adaptive capacity, which consequently increases their risk of extinction. In Europe, Taxus baccata is among a number of tree species experiencing strong habitat fragmentation. However, there is little empirical data on the population genetic consequences of fragmentation for this species. This study aimed to characterize local genetic structure in two natural remnants of English yew in Poland based on both amplified fragment length polymorphism (AFLP) and microsatellite (SSR) markers. We introduced a Bayesian approach that estimates the average inbreeding coefficient using AFLP (dominant) markers. Results showed that, in spite of high dispersal potential (bird-mediated seed dispersal and wind-mediated pollen dispersal), English yew populations show strong kinship structure, with a spatial extent of 50–100 m, depending on the population. The estimated inbreeding levels ranged from 0.016 to 0.063, depending on the population and marker used. Several patterns were evident: (1) AFLP markers showed stronger kinship structure than SSRs; (2) AFLP markers provided higher inbreeding estimates than SSRs; and (3) kinship structure and inbreeding were more pronounced in denser populations regardless of the marker used. Our results suggest that, because both kinship structure and (bi-parental) inbreeding exist in populations of English yew, gene dispersal can be fairly limited in this species. Furthermore, at a local scale, gene dispersal intensity can be more limited in a dense population.

A checklist of endemic plants on the Korean Peninsula

Abstract: In order to organize a new checklist for endemic vascular plants of the Korean Peninsula, 358 taxa of the Korea Forest Service and 375 taxa of the National Institute of Biological Resources were reviewed. In addition, the names of previously published endemic plants above the rank of variety were checked up to 2016. From the two lists, a total of 444 taxa were identified. Among them, 289 taxa were common on the two lists, but 69 and 86 taxa were listed only by the Korea Forest Service and by the National Institute of Biological Resources, respectively. Taxonomic documents including journal papers and dissertations were examined with regard to the 444 taxa. In some cases, opinions of Korean experts in this field were also reflected. From the results, 312 taxa in total were recognized as plants endemic to the Korean Peninsula, while 132 taxa could not be included on the endemic list. On the other hand, 48 taxa, none of which existed on the two lists, were newly listed. In conclusion, the new checklist of vascular plants endemic to Korea was confirmed, with a total of 360 taxa consisting of 64 families, 172 genera, 297 species, 4 subspecies, 51 varieties and 8 hybrids. The new common name Halla-seol-aeng-cho is given to Primula farinosa L. subsp. modesta (Bisset & S. Moore) Pax var. hannasanensis (T. Yamaz.) T. Yamaz. Sillaphyton Pimenov (Deok-u-gireum-na-mul-sok) is newly identified as a genus endemic to Korea. However, Pentactina Nakai could not be included on the list of Korean vascular endemic genera.